You can have one in the chamber. Only law you need to worry about with vehicles is concealed weapons. There are some laws regarding shooting from the road you need to know:

Hunters can take only small game (except doves) and waterfowl within the right-of-way on foot. Thehunter must be within the right-of-way and the game must have taken flight from within or be flying overthe right-of-way.

The person must park or stop their vehicle as far to the right-hand side of the road as possible.• If the person who discharges a firearm is more than 50 yards from the vehicle, the doors on the side ofthe vehicle nearest the roadway must be closed, but the engine may remain running.• If the person who discharges a firearm is less than 50 yards from the vehicle, all of the doors of the vehiclemust be closed and the engine shall be turned off.• It is NOT legal to shoot small game and waterfowl that takes flight from a public right-of-way over a FederalRefuge or Indian Tribal Trust lands. If a State-licensed hunter shoots at a bird across the fence on eitherof these lands, the hunter may be subject to arrest by Federal Fish & Wildlife officers.• Small game and waterfowl taken from the right-of-way but falling onto private property can be retrievedby unarmed hunters on foot.

See page 42 of SD hunting handbook, available online at the Game and Fish website.